I have an FX4 with max tow pkg. Getting 17 mpg combined driving. Biggest disappointment so far has been towing mileage. Towing a 30' TT at a weight of around 8000 lbs, I've averaged about 8.5 mpg. Did a short test at different speeds (using the truck's fuel monitor) and got about 10mpg at 55 mph, 9mpg at 60 mph, and 8 mpg at 70 mph.